1. Field
The present teachings relate to RF (radio frequency) circuits. More particularly, the present teachings relate to methods and devices for overcoming insertion loss in an RF transmit and/or receive system.
2. Description of Related Art
Radio frequency (RF) devices, such as cell phone transmitters, are becoming increasingly complex due to additional frequency bands, more complex modulation schemes, higher modulation bandwidths, and the introduction of data throughput improvement schemes such as simultaneous RF transmission and/or reception within a same or different, but closely spaced, bands or channels within a band (e.g. voice, data), and aggregate transmission wherein information is multiplexed over parallel RF transmissions. Due to the higher complexity of transmit/receive paths (transmit and/or receive paths) of a front-end stage used in such RF devices, which can include devices with various impedance characteristics, such as duplexers, diplexers, switches, etc., and the coupling of such transmit/receive paths to one or more common antennae, impedance of an inactive transmit/receive path can couple to the impedance of an active transmit/receive path and thus create an associated resonance in the active transmit/receive path. In some cases, such resonance can take place at a frequency within a frequency band of the active transmit/receive path and therefore can adversely influence performance of the active transmit/receive path, such as, for example, a deterioration of a corresponding insertion loss.